A multi-centre, observational, cross sectional study to evaluate the use of oxidized vs fresh tea tree oil (TTO) in patch testing for dermatitis in otherwise healthy patients


Current models of identifying prevalence of contact dermatitis from tea tree oil (TTO) rely on patch testing 5% oxidized TTO. This is in stark contrast with most other essential oils, which are tested as fresh oils at 2% concentrations. This testing and diagnostic approach produces an inaccurate diagnosis at the patient level and an inaccurate prevalence of contact dermatitis from TTO at the public health level.
This is caused by utilizing tests which measure contact dermatitis from oxidized TTO rather than dermatitis actually caused by fresh TTO.
This study will focus exclusively on patients with a self diagnosed reaction to TTO. This patient population will include patients who have legitimate reactions to TTO, fresh or oxidized, as well as those who do not.
To achieve 95% power with .05 significance, assuming a 4:1 ratio of oxidized: true TTO reactions, a sample size of 42 is required.


Tea Tree Oil

Research Organisation


Project Code


Project Stage


Project Start Date

Wednesday, February 9, 2022

Project Completion Date

Thursday, September 15, 2022

National Priority

TTO-Increasing demand